Jonah Lomu tells precious few stories about his past, but this one is a favourite. He invites you to imagine him as a poor, none-too- innocent Polynesian kid of 13, who spends his empty days hanging around the meanest streets in New Zealand. A mugger spots him sitting alone on a pavement in Mangere East, a particularly volatile district of south Auckland, and orders him to hand over his shoes. Lomu slowly raises himself from the floor... and keeps on rising until he towers over his would-be assailant. The mugger staggers backwards, says something along the lines of "Sorry, I've changed my mind" and disappears into the distance.

Jonah Lomu tells precious few stories about his past, but this one is a favourite. He invites you to imagine him as a poor, none-too- innocent Polynesian kid of 13, who spends his empty days hanging around the meanest streets in New Zealand. A mugger spots him sitting alone on a pavement in Mangere East, a particularly volatile district of south Auckland, and orders him to hand over his shoes. Lomu slowly raises himself from the floor... and keeps on rising until he towers over his would-be assailant. The mugger staggers backwards, says something along the lines of "Sorry, I've changed my mind" and disappears into the distance.

Four years ago in Cape Town on a warm World Cup semi-final afternoon at the intimate and intimidating Newlands stadium, 15 white-shirted Englishmen were not in the happy position of being able to disappear, much to their collective chagrin. They had no option but to accept the punishment being dished out by a 6ft 5in, 19-stone All Black wing as he produced what is still considered to be the single most extraordinary individual performance in the 128-year history of international rugby union. In the opinion of Jeremy Guscott, one of the few English players of his generation whose fame transcends the confines of his sport, "Jonah was born that day".

So he was, in the public sense. Those in the know had cottoned on to Lomu a year previously in 1994, when he was picked from nowhere to face the touring French. (At 19 years and one month, he was the youngest player ever to be selected for an All Black Test team). Subsequently he illuminated a major seven-a-side tournament in Hong Kong, which is where the phrase "Jonah the freak" was initially coined by chastened opponents who were in search of an excuse, if not an explanation, for what had just happened to them. But it was in South Africa, in '95, that he revolutionised the game.

Even though the Springboks won the Webb Ellis Trophy - in the final, they successfully worked out a way of halting the runaway tractor on New Zealand's left flank - it was Jonah's tournament. He scored seven tries in five games, four of them against England. Occasionally, he ran round opponents; more often, he ran through them or over them. It is said that when Rupert Murdoch decided to buy southern hemisphere rugby lock, stock and barrel for £260m, it was largely on the strength of Lomu.

"He just wanted Jonah on his television screen," said one executive of BSkyB at the time.

Rugby had never seen a phenomenon like it, either on the field or off it. Hero-worship was not entirely new to the game; the Welsh had been so successful in canonising their mud-spattered legends - Gareth, Barry, JPR and JJ - that surnames were rendered obsolete. The French had the Gauloise-puffing genius from super-sexy Biarritz, Serge Blanco, while the Australians fell in love with the fast-talking Pom-baiter David Campese. As for the English... well, there was Will Carling, doing his strong, silent bit for Queen and country and earning himself a small fortune in the process. But Lomu was different, a one-man cabaret act who appeared to be able to surround the opposition all on his own. "Remember, rugby is a team game," read one fax to the New Zealand team hotel on the eve of the '95 final. "All 14 of you make sure you pass it straight to Jonah."

Had it not been for union's sudden abandonment of the amateur ethic and its embrace of professionalism in the immediate aftermath of the tournament in South Africa, its most bankable crowd-puller would have taken someone else's shilling and switched sports. Big-time rugby league outfits had been pursuing him for months; rather more temptingly, the Dallas Cowboys gridiron team offered him $6m to don the crash-helmet and set his sights on the Superbowl. The New Zealand Rugby Football Union had to find big bucks to keep him on the straight and narrow, and with Murdoch's timely millions pouring into its coffers, it was soon in a position to strike a deal. On 9 July 1995, the All Black hierarchy announced that the name Jonah Lomu was now a registered trademark, and that they had commercial authority over its use. Jonah was New Zealand rugby and vice versa.

And now he is in London: over-sized, over-paid and over here, you might say. This afternoon at Twickenham, England play New Zealand in a World Cup pool game. It is not a final, or even a knock-out match; whatever the outcome, both countries will still be in the competition tomorrow morning. Yet Lomu's presence in the All Black side has sent a charge of sporting electricity coursing through the occasion. The boy from the wrong side of the Auckland tracks has recovered both from a drastic slump in form and, far more importantly, from a debilitating kidney disorder, to become big box office once again.

As with all rags to riches stories, it might have been utterly different. Lomu was born in Auckland - not the swanky Auckland of a thousand yachts, but the violent Auckland of the Lee Tamahori movie Once Were Warriors - in 1975, during one of the All Blacks' rare fallow periods. His parents, Semisi and Hepi, were Tongan immigrants, and they decided that their son should spend his infancy back home in the islands, perhaps so he could see and understand the world through their eyes. "Tonga runs deep in me, like still waters," said Lomu, who did not return to New Zealand for five years. "You can't escape your roots. It's like a calling and it's shaped the way I am. Tonga is a beautiful place. You cannot help being at one with nature."

Auckland, on the other hand, was anything but beautiful. Contrary to recent Lomu mythologising, he never fell wholly amongst thieves. There were street fights, of course, but he would have needed to run the 100 metres rather quicker than his very respectable best of 10.98 seconds to escape trouble altogether. Mangere, riven by Maori gangs and Samoan gangs and Tongan gangs, was trouble writ large, as was the nearby district of Otara. It was in Otara that Lomu's uncle and cousin were murdered. Jonah was 12 at the time. But as the journalist Phil Shirley pointed out in his boldly informative unofficial biography of Lomu, Blood and Thunder, "he was no Mike Tyson. When it comes to troubled childhoods, Lomu is not in Tyson's league". He had a sharp temper and could look after himself, but he was no dyed-in-the-wool villain.

There were two escape routes: one via his devout mother, the other via his precocious sporting talent. The two roads converged almost immediately. Aware of the perilous pitfalls of life in the urban badlands of Auckland, Hepi Lomu sent her son to board at the strictly Methodist Wesley College, near Pukekohe, some 35 miles south of the Mangere hell-hole. At 13, he stood well over 6ft and tipped the scales at more than 16 stone; the physical gifts that would help him transform the only sport that has ever really mattered to New Zealanders were already in evidence. So too was his competitive prowess. At one school athletics meet, he entered two sprints, a relay, a hurdles race, two throwing competitions, the long jump and the triple jump. He won the lot.

But the oval ball is king in All Black country and it was as a rugby player that he caught the eye of every coach for miles around. In his early years at Wesley, he preferred the individualistic immediacy of rugby league to the more technical challenge of union. The NZRFU soon brought pressure to bear, though; of all the serious rugby-playing peoples on the planet, the New Zealanders are the most proficient at identifying, harnessing and maximising their native talent. Not that a teenager of Lomu's dimensions needed a great deal of identifying. He was fast-tracked through the system at such velocity that he was playing National Provincial Championship rugby at the age of 18.

From there it was a relatively short step to centre stage. His early Test appearances were nothing to write home to Hepi about; he looked crude, cumbersome, confused and some way short of optimum fitness during his first international summer in 1994. But he was acute enough to listen to his fellow All Blacks, who told him that he could either put his heart and soul into it and make a life for himself, or head on back to the wooden shacks and gang culture of Mangere. And within a year, he was to have South Africa's Rainbow Nation hanging on his every move.

It would not be long, however, before the whole of New Zealand was staring at Lomu in less propitious circumstances. First, there was the blip: in March 1996, he married a 19-year-old South African, Tanya Rutter, without informing his parents. "I was scared they wouldn't let me do it," he explained during a subsequent television interview.

Then came the breakdown. Almost three years ago he was diagnosed as suffering from nephrotic syndrome; a kidney specialist prescribed a six-month course of chemotherapy as the only way of stabilising the condition, warning that while his patient's life was not in any obvious danger, the same could not be said for his sporting career.

Happily, the condition did stabilise; three months after his 22nd birthday, he was cleared to resume training. He was still on a dozen tablets a day, the effects of which played havoc with an appetite that had always been on the large side of immense. During the halcyon weeks of the '95 World Cup, Lomu would think nothing of wolfing down an enormous bowl of fresh fruit intended for the entire All Black party. Now, though, he was spending some serious time at the trough. "The darkest period was when I found myself eating two chickens a day," he recalled recently. His weight ballooned to 148 kilos - somewhere in the region of 23 stone - and before he could even dream about resuming his rugby career in any meaningful sense, a quarter of that poundage would have to be lost.

According to John Hart, the New Zealand coach, Lomu's achievement in getting himself in shape for the current tournament says everything about the man. According to Lomu, it says everything about his God. Many All Blacks of Pacific island descent are deeply religious: Michael Jones, an Aucklander of Samoan parentage and perhaps the most sublimely gifted forward ever to play the game, happily sacrificed large chunks of his international career by refusing to play on Sundays. Lomu has always turned out on the Sabbath, if required to do so, but that does not necessarily make him any less observant. His is a pantheistic, individual approach to belief. "My heart is an open book before God," he has been quoted as saying. "I talk to the Lord often, even before games. I ask Him to protect all the players."

And, by heaven, they need protecting when Lomu is in full flood. "I suppose you might stop him with an elephant gun," said Brian Moore, the acerbic English hooker, after the humiliation of Cape Town. "On that day, Lomu played with a dynamic power above and beyond anything we had ever experienced," recalled Jack Rowell, the then England coach, in the columns of this newspaper only last week. But in all the rainforests of newsprint devoted to the largest physical specimen ever to play rugby for New Zealand, one short, snappy description hits the spot most accurately. "There's no doubt about it," said Gavin Hastings, the Scotland captain, after a profoundly painful confrontation with Lomu in 1995. "He's one big bastard."

Life StoryBorn: 12 May 1975 in Auckland, New Zealand, weighing 11IbFamily: Father, Semisi and mother, HepisipapiuEducation: The Wesley College, Pukekohe, near AucklandCareer: Counties Manukau rugby team since 1993. Auckland Blues in the Super 12 tournament (1996-1998). Waikato Chiefs in the Super 12 tournament since 1998. Youngest ever to play for the All Blacks (1994). New Zealand winger in the World Cup in South Africa (1995). Took a break from Rugby to recover from illness (1997-1998). He wins his 34th New Zealand Cap today.Earnings: NZ$400,000 a year (£130,000). Worth NZ$3 millionMarriage: Married South African Tanya Rutter, 17 March 1996. Separated in October 1998. Lives with girlfriend Teina StaceLow point: Diagnosis of the chronic kidney condition, nephrotic syndrome, in 1997Height: 6ft 5inWeight: Approximately 19 stonesCollar size: 22 inChest size: 48 inNickname: The dark destroyer Loves: Eating fruit, especially plums, and listening to reggae.They say: 'He is the same weight as before the last World Cup and he is looking magnificent. He looks like if you tried to hammer a nail into him, you couldn't.' (Manager, Phil Kingsley-Jones)He says: 'My mother is the only person I'm scared of. She clips me around the ear if I get too big for my boots.'